The disclosure of Japanese Patent Application No. 2000-300190 filed on Sep. 29, 2000 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of Invention
The invention relates to a vehicle wheel rotation detecting system, which is incorporated in the vehicle.
2. Description of Related Art
JP-A-2000-187039 discloses a system for detecting a rotating direction of a rotating object, such as a vehicle wheel, in accordance with a state of phase of an output detected by a pair of sensors mounted to the respective rotating objects.
When employing the aforementioned system for detecting the rotating state of the rotating object, the resultant output of the rotating direction may possibly be incorrect and different from an actual rotating direction owing to the influence of an external magnetic field or a magnetic environment. The incorrect output as described above is undesirable in view of an optimal operation of an on-board device including an anti-lock braking system (hereinafter referred to as an ABS), or the like.
It is an object of the invention to provide a system which detects a rotating state of a vehicle wheel so as to avoid an output of incorrect rotating direction.
A vehicle wheel rotation detecting system is provided with a rotating member which rotates together with a vehicle wheel, a detected portion, which is provided in the rotating member, a detector which generates a signal in response to a passage of the detected portion, and a rotating direction detector which detects a rotating direction of the vehicle wheel in accordance with an output of the detector, the rotating direction being adapted to be used by an on-board system. In this system, when a rotating speed of the vehicle wheel is equal to or greater than a predetermined value, a change in an output of the rotating direction is inhibited.
If the rotating speed of the wheel is equal to or greater than a predetermined value, the vehicle wheel rotation detecting system is operative to inhibit the change of an output of the rotating direction. As a result, an output of the incorrect rotating direction may be prevented. It is conceivable that the rotating direction cannot be turned in an abrupt way because of an inertial force. Accordingly, in the state in which the rotating speed of the wheel is equal to or greater than the predetermined value, detection of incorrect rotating direction may be easily prevented by the control to inhibit the change of the output of the rotating direction.